Volume 13 Issue 2

Various biomass resources have been fabricated and devoted to the application of energy storage. Rice husk is a promising candidate for a supercapacitor, but its conductivity and surface to weight ratio are much poorer than commercial activated carbon. In this paper, the byproduct of rice husk gasification power generation as a raw material was boiled with KOH solution and activated by CO2 to prepare activated carbon. The authors selected the appropriate activation temperature and lye mass fraction to prepare the activated carbon electrode. A scanning electron microscope was used to characterize the surface topography. The porosity of the carbon was detected by nitrogen adsorption. The electrochemical behavior was determined by using galvanostatic charge-discharge, cyclic voltammetry, and impedance spectroscopy techniques. When the activation temperature was 850 °C and the mass fraction of the KOH solution was 30%, the Brunauer-Emmett-Teller specific surface area of the activated carbon reached a maximum value of 1383 m2/g and the specific capacitance was 168 F/g at 250 mA/g with good electrochemical performance.

This study focused on the performance of dragon fruit foliage as a natural, plant-based coagulant to replace chemical coagulants for the treatment of three-phase decanter palm oil mill effluent (POME). Palm oil mill effluent is a high strength wastewater with high chemical oxygen demand (COD), suspended solids (SS), and turbidity as compared to other sources of POME in mills. The first objective of this study was to determine the optimum operating conditions of the coagulation-flocculation process using the plant-based coagulant in terms of pH and dosage. The second objective was to measure the percentage removal of COD, SS, and turbidity using the coagulant to treat the POME. The pH values and dosages used in the coagulation-flocculation process were in the range of two to ten and 300 mg/L to 800 mg/L, respectively. This study revealed that the optimum percentage removals of COD, SS, and turbidity were 48.7%, 98.8%, and 99.2%, respectively, at the best operating conditions of pH 2 and a coagulant dosage of 300 mg/L. In conclusion, the dragon fruit foliage, plant-based coagulant was found to have potential and could be used in the pretreatment stages to substitute chemical coagulants for the treatment of POME.

Walnut meal and polyethyleneimine (PEI) were used as raw materials for producing an environmentally friendly adhesive to bond plywood, and the shear strength was investigated. The results showed that the walnut meal-based mixture adhesive can successfully be used for the production of plywood. However, the shear strength of plywood clearly changed with different raw materials ratios. Both the wet and hot water strength were improved with increasing polyethyleneimine (PEI) content. This indicated that PEI had an important contribution to the water-resistance of the mixture system, and considering the cost of PEI, a walnut meal powder and PEI weight ratio of 70:30 was recommended. The effects of walnut protein solution thermal processing time and temperature were also studied. It was beneficial to enhance the wet and hot water shear strength of plywood to increase the thermal processing time and temperature. The investigation of curing characteristic of mixture system and monomer ingredient via differential scanning calorimetry (DSC) revealed that the curing peak temperature of the mixture system was similar to PEI, and that a chemical reaction should be made between them during the heating process. Lastly, the thermal characteristic of the mixture system was investigated via thermogravimetric (TG) analysis, where good thermal resistance was displayed.

Wood chip transportation is a widespread practice in Poland, with distances between forest sites and power or heating plants reaching 300 km and truck transport times of up to 6 h. Because the basic parameter affecting biomass quality for energy production is moisture content, the objective of the presented economic analysis was to determine its effect on the price of wood chips transported by semi-trailer trucks. This paper considered the possibility of drying biomass in the semi-trailer. No external energy consumption was envisioned; the heat needed for drying was obtained from the truck cooling or exhaust systems via heat exchangers. The moisture content of transported biomass had a dual effect on the final truckload price. While it increased biomass amount by adding to its weight, it decreased its price by lowering its calorific value. Mathematical analysis showed that a decrease in wood chip moisture content increased truckload price, justifying research on technological improvements of this process. Simulations indicated that by reducing moisture content during transportation, biomass suppliers increased their revenues approximately € 3.6 to € 30.0 per truckload, which translates into annual financial profit ranging from tens of thousands of euros (EUR) to more than € 23,810.

Poplar and black locust plantations are widely used for production of raw materials for biofuel. In this study, the main characteristics affecting energy content were evaluated for 2-year-old plantations obtained from 3 different sites of various qualities were evaluated. The ‘I-214’ poplar and the black locust had smaller (16 to 21%) bark ratios, while the ‘Kopecky’ poplar had a higher (22 to 26%) bark gain yield. The black locust had a higher basic density than that of the poplars, which were wood (446 kg/m3) and bark (402 kg/m3). The higher heating value of the bark of the black locust (19.51 to 19.59 MJ/kg) and of the ‘Kopecky’ (19.58 to 19.86 MJ/kg) was greater than that of the wood; in the case of the ‘I-214’ (19.59 to 19.81 MJ/kg), the higher heating value of the wood was higher. The ash content of the bark (4.50 to 8.22%) was several times greater in the case of poplars and black locust than that of the wood (0.46 to 1.29%). In the case of the wood, the ash content increased by the degradation of the site’s quality. There were remarkable differences between the black locust and the poplars, as well as the individual poplar clones among the main energetic characteristics.

In order to form a firm root plug for the mechanical transplantation, modified urea formaldehyde (UF) resins were applied to bond coir based substrate and form substrate blocks. The physical and chemical structure, thermal stability, and crystallinity of the substrate blocks before and after nursery seedlings were characterized. The results showed that the -NH2 and -OH in the substrate reacted with the modified UF resins to form macromolecular structures. There was almost no difference between the XRD spectra of substrate blocks before and after the growth of seedlings. The modified resins in the substrate block were cured in the form of colloidal particles. The substrate block contained 53.8 At% carbon, 15.0 At% nitrogen, and 23.5 At% oxygen. When compared with the original substrate, the height, stem diameter, root length, and leaf area of tomato seedlings grown in substrate block were improved by 56.1%, 43.3%, 1.3%, and 63.3%, respectively. The qualification percentage of the substrate block was 94.3%, which was well above that of the original substrate (83.4%) according to JB/T 10291 (2013) standards. The substrate block bonded by the modified UF resins was suitable for tomato seedlings growth.

Rice bran was introduced as an alternative nitrogen source to Hestrin and Schramm (HS) medium in HS Acetobacter xylinum culture media in bacterial cellulose (B.C) synthesis. The results indicated an unchanged composition of crude protein per increase in incubation days while diluted protein increased with incubation period. Fourier transform infrared spectroscopy (FTIR) results showed the absorbance of OH groups. It was confirmed that the BC yield was directly proportional to the rice bran content. A general observation indicated a gradual transformation from a highly crystalline structure to a very amorphous structure as rice bran content increased with the endothermic decomposition of samples being recorded between 113.5 °C and 125.6 °C.

Activated carbons (ACs) were obtained from roots of Salvia miltiorrhiza Bunge (Danshen) followed by chemical activation with potassium hydroxide (KOH). The ACs were characterized by nitrogen adsorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and electrochemical testing. Results showed that ACs from cultivation sites in Pingyi (ASPY), possessed many micropores, a dominant amount of mesopores, and few macropores. They achieved a value of 1615 m2/g of specific surface area calculated by the Brunauer-Emmett-Teller (BET) method with numerous oxygen-containing functional groups. Electrodes fabricated with ASPY particles exhibited excellent double-layer specific capacitance (245 F/g), while the other two marked as ASFC (ACs from Fangcheng) and ASZJ (ACs from Zhongjiang) reached values of 163 F/g and 81 F/g, respectively, at a current density of 1 A/g in 6 mol/L KOH electrolytes. Electrodes made by ASPY had a good cyclic stability for 1000 cycles at a potential range from -1 V to 0 V and lower equivalent series resistance (ESR). Meanwhile, the authors found that roots of Danshen that grew in different cultivation sites were remarkably different while they were activated, which was the same with electrochemical properties of the electrodes fabricated by ACs.

Microwave assisted maleic acid (MA) pretreatment is a potential method for biomass processing. The aim of the present study was to determine the optimum conditions for pretreatment of oil palm empty fruit bunch (OPEFB) for bioethanol production, as well as to understand the changes of functional groups in the pretreated OPEFB. The optimum pretreatment conditions with the highest reducing sugar yield (RSY) (47.21%) were 190 °C for 2.5 min with 1% MA. The temperature had more influence on the chemical components and RSY than the other pretreatment parameters. More severe pretreatment conditions tended to dissolve more sugar into the hydrolysates. Structural changes occurred in the OPEFB pretreated with MA and sulfuric acid, which were observed by the absence of certain functional groups. The simultaneous saccharification and fermentation (SSF) of MA-pretreated OPEFB produced ethanol with a concentration of 18.9 g/L and yield of 0.43 g ethanol/g cellulose after pretreatment, or equivalent to 76.6% of theoretical maximum yield. Microwave assisted MA pretreatment of OPEFB successfully increased the RSY about 300% compared to the untreated one. The MA pretreatment removed hemicellulose and lignin. The highest ethanol concentration and yield were produced after 48 h of SSF of the OPEFB pretreated with MA.

Recently, polymer nanocomposites have been fabricated using carbon nanotubes (CNTs) as reinforcement nanofillers. However, the effect of incorporating CNT/polymer into hybrid composites with natural fibre is not clear. This study investigated the effect of using multi-walled carbon nanotube material (MWCNT) as the nanofiller on the tensile and flexural properties of bamboo/glass fibre hybrid composites. Composites containing various weight fractions of CNTs (0.1 wt.%, 0.3 wt.%, 0.5 wt.%, and 1.0 wt.%) were compared with the control hybrid composites. The hybrid composites were prepared with epoxy resin. The experimental results revealed an increase in the tensile strength of the composites with the addition of up to 0.5 wt.% CNTs (+7.7% over the control hybrid). However, beyond this value, i.e., with 1.0 wt.% CNT additives, the composite strength showed a remarkable decrease (-36.8% compared with the control hybrid). Moreover, introducing CNTs into hybrid composites resulted reduced the flexural properties with increasing weight fractions as low as 8.45% compared with the controls. In sum, the tensile properties increased with the addition of up to 0.5 wt.% CNTs, but there was a decrease in the flexural properties.